Watch: McGregor rubs Mayweather's 'peanut head,' mimes slap

Prior to the final stop of Conor McGregor and Floyd Mayweather's world tour, UFC president Dana White said as long as the two fighters don't lay a hand on each other before the bout, he'll be happy.

He wasn't happy Friday.

As "The Notorious" strutted around the ring berating his 40-year-old opponent in London, McGregor made the first contact, rubbing Mayweather's bald "peanut head" before miming a slap.

It's hard to tell who's in whose head at this point.